A number of different knee prostheses have been developed; these falling into two general types, the first type being of the hinged variety, wherein a shaft such as a metal nail or spike, is driven into each of the bones and the two shafts are then hingedly connected together, as by axle means of one form or another. The second form of prosthesis involves cutting away of the mating surfaces of the femur and tibia and replacing these surfaces by members having specially designed mating surfaces, wherein one of the members slides across the other, more or less in the manner that the femur slides on the tibia in a normal knee joint. While this form of prosthesis operation has been performed before, this was the usual extent of the operation, and although results were generally satisfactory, a number of problems remained. It has now been found that if a new articulating surface is placed on the posterior aspect of the patella, much better results are obtained. The present invention makes use of an improved design for the femoral and tibial bearing surfaces, as well as making provision for a patellar articulating metal implant. Their design provides for knee joint stability as well as low friction articulation.
The need for the knee prosthesis strikes across the entire population. Arthritis of the knee, from injury or disease, is common and the pain, instability and stiffness which may result is totally disabling to the afflicted individual. Treatment by stiffening the knee is unacceptable, as the person is not then able to arise from a chair or step up a curb. Only prosthetic replacement of the knee joint avoids this disability and only the three-part joint offers the opportunity to walk up the stairs and climb slopes without pain.